Oil prices fell for a second day Wednesday over concerns about economic turbulence in Europe, China and the U.S.

Benchmark oil was down 23 cents to $91.66 per barrel at midday Bangkok time in electronic trading on the New York Mercantile Exchange. The contract dropped 59 cents to end at $91.89 per barrel in New York on Tuesday.

Brent crude, which is used to price international varieties of oil, fell 47 cents to $111.10 per barrel on the ICE Futures exchange in London.

Investors remain concerned about Europe's ongoing financial crisis after Spain's prime minister said a request for bailout funding isn't imminent.

Slower growth in China, which is a huge importer of oil, has also kept a lid on oil prices. Slower growth can cut demand for oil and other energy products.

Worries have also intensified that the U.S. economy will fall off a "fiscal cliff" at the end of the year. That's when tax increases and deep spending cuts will take effect unless Congress reaches a budget deal. A recession could follow.

"There is downside risk in the overall market," said Ric Spooner, chief market analyst at CMC Markets in Sydney. "Oil is one of those commodities where I think demand is well-covered by current supply capacity."

In other Nymex energy futures trading:

— Natural gas fell 3.1 cents to $3.50 per 1,000 cubic feet. It ended at $3.531 Tuesday, a high for the year. The price is 85 percent above the low for the year of $1.91 reached in April.

— Heating oil was down 0.2 cent at $3.123 a gallon.

— Wholesale gasoline dropped 1 cent to $2.86 per gallon.